Embodiments of the present invention relates to a semiconductor device and a method for manufacturing the same, and more specifically, to a semiconductor device and a method for manufacturing the same that comprises a gate using a graphene.
Many of today's electronic appliances include a semiconductor device. The semiconductor device includes electronic elements such as a transistor, a resistor and a capacitor. These electronic elements are designed to perform a partial function of the electronic device, and integrated on a semiconductor substrate. For example, electronic devices such as a computer or a digital camera include a memory chip for storing information and a processing chip for controlling information. The memory chip and the processing chip include electronic elements integrated on a semiconductor substrate.
Semiconductor devices are required to be highly integrated in order to satisfy the consumer's demand for excellent performance and inexpensive price. As the integration of the semiconductor memory device has become higher, the design rule has been reduced so that a pattern of the semiconductor device becomes micro-sized. Due to limits in characteristics of silicon material and in the manufacturing process, high integration and high performance of the silicon-based semiconductor device are difficult.
As a result, research on the next generation device has been made to overcome the limits of the silicon-based semiconductor device. For example, a nano structure such as a carbon nano tube (CNT) is applied in order to manufacture a micro-sized device with excellent performance. The carbon nano tube has a diameter in the tens of nano meters, thereby facilitating micronization of the device with high mobility, high electric conductivity, high thermal conductivity and strong mechanical intensity. This carbon nano tube has received much attention to overcome limits of the existing device.
However, since there are problems in applying the carbon nano tube to the semiconductor device, it is difficult to obtain the semiconductor device applied with the carbon nano tube. For example, it is difficult to compose a carbon nano tube with reproducibility and handle the composed carbon nano tube. In order to manufacture a device using a carbon nano tube, a technique of aligning a carbon nano tube in a desired region of a substrate for manufacturing a device. Also, it is difficult to apply a carbon nano tube along with other nano structures in one device, which limits the manufacturing of various high performance devices. As a result, the development of techniques to manufacture a semiconductor device using a carbon nano tube is needed.
Meanwhile, as the design rule of the semiconductor device is reduced, the corresponding channel length is also decreased, which results in a decrease of the channel length of cell transistors as a storage unit as well as transistors of a peripheral circuit. As a result, it is difficult to obtain a target of a threshold voltage (Vt) of a transistor required in a specific device by the existing plannar transistor structure. Although a technique using a three-dimensional gate has been developed in order to overcome the problem, a complicated technique is required to apply the three-dimensional gate, which results in defects.